When setting up to siege someone, we've got our army in a camp outside their city, right? So, during that time, can the army of the city come out to attack the camp? For that matter, can anyone else attack the camp - say an ally or even just a neutral player who feels like helping out a fledgling newbie city or something by killing the would-be attackers?

And on camps... If we can attack camps- would this function like a siege on a low level city, or not a siege at all but a field-based battle? How does this work? Is it even existent?

When setting up to siege someone, we've got our army in a camp outside their city, right?

Correct, and off to a good start. You have a small camp that has either A) no fortications, B) light fortifications such as palisades, or C) heavy fortifications such as, perhaps, heavier walls. The fortifications present are based on your selection when you choose to lay siege to the enemy and will cost varying amount of gold and wood.

Quote:

So, during that time, can the army of the city come out to attack the camp?

They certainly could if they so desired. Your camp now exists on the same map as the defending player's home city, and as such he could preemptively come out to attack you if he or she believed that to be the wisest move. I wouldn't be surprised in the least if the average orc player took this route, as their defenses generally aren't as strong and they may be better served fighting you on open terrain, away from the gates.

Quote:

For that matter, can anyone else attack the camp - say an ally or even just a neutral player who feels like helping out a fledgling newbie city or something by killing the would-be attackers?

I don't think any random "Sir Joe Noobishness" could come to the aid of the besieged player on a whim. It is possible, however, that the defending player may have an Alliance with another player. Said Alliance would request the third player to come to the defender's rescue or be penalized for breaking the terms of the Alliance. In this case, you--the attacker--would likely be presented with a timer that counted down to the arrival of the defenders ally. When his troops arrived, he could attack your camp or even your army's flank, crushing it against the defender's walls. This would add a sense of urgency to the match and force you to think and act quickly, rather than stall for time.

Quote:

And on camps... If we can attack camps- would this function like a siege on a low level city, or not a siege at all but a field-based battle? How does this work? Is it even existent?

I believe that camps don't have gates, so a siege in the traditional sense would be kind of moot. Likely, you're looking at the defender's army rolling into your camp and taking out your reserves before you get a chance to use them. If the heavily-fortified camps did have gates, however, then yes, it would be like a tiny, cute little siege aimed at wiping out the camp in some way--perhaps by destroying some special "outpost" building at its heart. In general, the siege of any city would end when the attacking player decides to retreat and withdraw his remaining forces from the region.